1. Field of the Invention
The present invention relates to a method for surface treatment of a gold-plated body, a surface-treated product, a method for the manufacture of a gold-plated body, a gold-plated body, and an immobilization method which make it possible to immobilize a large number of sulfur-containing molecules.
2. Description of Prior Art
A technology for immobilizing sulfur-containing molecules having Sxe2x80x94H groups, Sxe2x80x94S groups, and the like on the surface of gold (Au) (bonding of Sxe2x80x94H groups and gold is described in J. Am. Chem. Soc., No. 111, p. 321xcx9c, 1989, by C. D. Bain et al., and in Anal. Chem. No. 70, p. 2396xcx9c, 1998, by J. J. Gooding et al.) has been known in a variety of fields such as immobilization of probes in gene detection (target gene probe), immobilization of self-assembled monolayers (SAM) as resists (photosensitive agents), and the like.
Gold-plated bodies prepared by plating gold by a usual plating method on the surface of a substrate such as alloy substrate have been used as gold serving as immobilization substrates for such sulfur-containing molecules.
However, a problem associated with such gold-plated bodies was that only a small amount of sulfur-containing molecules could be immobilized on the surface thereof. This was apparently because the orientation of gold crystal structure on the surface of gold plated body was not constant which resulted in a decreased amount of bonds (coordination bonds) between gold and Sxe2x80x94H groups or Sxe2x80x94S groups contained in the sulfur-containing molecules.
Appropriately changing gold plating conditions such as temperature in the process of forming a gold-plated body was considered as a means for obtaining a constant orientation of surface structure of the gold-plated body and immobilizing a large amount of sulfur-containing molecules on the gold-plated body. However, changing of such conditions was in reality difficult.
Accordingly, it is an object of the present invention to provide a method for surface treatment of a gold-plated body, a surface-treated product, and an immobilization method which make it possible to immobilize a large amount of sulfur-containing molecules.
The results of the intensive study conducted by the inventors demonstrated that the above-described object can be attained by a method by which the surface of a gold-plated body after gold plating is annealed within the specific temperature range.
The present invention is based on this finding and it provides a method for surface treatment of a gold-plated body, by which the surface of the gold-plated body is subjected to annealing at a temperature of 350 to 790xc2x0 C. so that a large number of sulfur-containing molecules could be immobilized.
The present invention also provides a surface-treated product of the gold-plated body that was treated by the above-described surface treatment method.
The present invention also provides a method for the immobilization of sulfur-containing molecules by which a large number of sulfur-containing molecules are immobilized on the surface treated product of the gold-plated body that was treated by the above-described surface treatment method.
Furthermore, the inventors have also found that the above-mentioned object can be attained by a gold-plated body manufactured from a starting material having a specific additive added thereto.
The present invention is based on this finding and provides a method for the manufacture of a gold-plated body by which surface gold crystals are formed from a starting material comprising a crystal growth enhancer, this method manufacturing a gold-plated body allowing a large number of sulfur-containing molecules to be immobilized on the surface.
Moreover, the present invention provides a gold-plated body obtained by the aforesaid manufacturing method.
The present invention also provides a method for immobilizing sulfur-containing molecules which immobilizes a large number of sulfur-containing molecules on the gold-plated body obtained by the aforesaid manufacturing method.